Wally has 400 cards. how many stacks of 10 cards can we make?

Solve the equation w^3 = 1,000 i honestly dont know how to punch this into a calculator pls

Can someone check if i did this correct. it’s number 4 if you’re wondering.

Assume that there is a 11% rate of disk drive failure in a year. a. if all your computer data is stored on a hard disk drive with a copy stored on a second hard disk drive, what is the probability that during a year, you can avoid catastrophe with at least one working drive? b. if copies of all your computer data are stored on four independent hard disk drives, what is the probability that during a year, you can avoid catastrophe with at least one working drive?